Formation of electrodes for magnetoresistive sensor

Abstract

Electrodes for a magnetoresistive sensor can be formed easily by a method wherein a double-layer structure of Mo and Al on a film of a magnetoresistive material such as permalloy is formed to have a predetermined pattern, firstly by exposing an Al layer to a chemical etching solution or subjecting the Al layer to the ion-milling treatment to give said Al layer said pattern and then subjecting a Mo layer to the plasma etching or reactive sputter etching treatment to give said Mo layer said pattern.

What is claimed is: 
     
       1. A method of forming electrodes for a magnetoresistive sensor comprising the steps of (a) providing a mask of a predetermined pattern on a double-layer structure comprising a Mo film of which at least a portion is formed on a magnetoresistive film and an Al or Al alloy film deposited on said Mo film;   (b) exposing said Al or Al alloy film to an etching environment to etch at least said Al or Al alloy film into said predetermined pattern; and   (c) processing, after the completion of said step (b), at least said Mo film to have a pattern corresponding to that of said Al or Al alloy film by a plasma etching or reactive sputter etching technique.   
     
     
       2. The method according to claim 1, wherein said Al or Al alloy film is etched by using a chemical etching solution in said step (b) and a Mo/Al reacted layer and said Mo film are etched in said step (c). 
     
     
       3. The method according to claim 1, wherein said Al or Al alloy film and said Mo/Al reacted layer are etched by an ion-milling technique in said step (b) and said Mo film is etched in said step (c). 
     
     
       4. The method according to claim 2, wherein the plasma etching is conducted in a gaseous atmosphere containing a halogen compound in said step (c). 
     
     
       5. The method according to claim 3, wherein the plasma etching is conducted in a gaseous atmosphere containing a halogen compound in said step (c). 
     
     
       6. The method according to claim 4, wherein said halogen compound is CF 4 . 
     
     
       7. The method according to claim 5, wherein said halogen compound is CF 4 . 
     
     
       8. The method according to any one of claims 1 to 7, wherein said magnetoresistive film consists of a ferromagnetic material containing Ni, Fe, Co, Cr and/or Ti as a main constitutent and exhibiting magnetic anisotropy. 
     
     
       9. The method according to claim 8, wherein said magnetoresistive film consists of a Ni-Fe alloy.